Today’s Question: Please clarify a basic concept: is there any way Photoshop can irreversibly, destructively change the original raw file, the file the camera produces?
Tim’s Quick Answer: No, Adobe Photoshop (and by extension Adobe Bridge) will not alter the original raw capture. When you process a raw capture, any applicable settings are saved in an XMP “sidecar” file rather than altering the original capture. When you process the image, such as with Adobe Camera Raw, you are creating a new derivative image based on the original raw capture.
More Detail: A raw capture is a unique file format, in that it isn’t truly an image file (such as a JPEG or TIFF file), but rather is a data file containing the information gathered by the image sensor at the time a photograph was captured.
As such, a raw capture needs to be interpreted by software after the capture, in order to create a true image file. In the context of Photoshop, that processing is typically handled using Adobe Camera Raw. You could also, of course, process the raw capture in Lightroom Classic and send the resulting image to Photoshop for further processing.
Within Photoshop it is absolutely possible to permanently alter an image in a “destructive” way. In other words, you could open an image, paint pixels over the top of that image, save and close the file, and never be able to get back to the unaltered original. That is not the case with a raw capture.
Any metadata updates that are applied to a raw capture in Photoshop (or Adobe Bridge) will be written to an XMP “sidecar” file alongside the original raw capture. When you open a raw capture in Photoshop, you’ll first need to process that raw capture using Adobe Camera Raw. When you are finished applying adjustment settings in Camera Raw, opening the image causes a new image to be created, based on the raw capture.
You can then of course save and process that derivative image. You could use a layer-based non-destructive workflow for that additional processing, or a “destructive” workflow that alters pixel values, depending on your preference. But at any time you could return to the original raw capture, reset the adjustment settings in Camera Raw if you prefer, and start over with an unaltered original capture.